Computer systems can store information as objects. Multiple ones of the objects may be of a same type. As such, these objects may have been generated based on a schema that identifies constraints on the structure and content of the objects. For example, the schema can identify the attributes that may be included in objects that are generated in accordance with the schema, and can further identify attributes that are required in the objects. The attributes can identify semantics of corresponding data values, although the schema may not include data values. Objects that are created in accordance with the schema, however, include at least some of the attributes from the schema and include corresponding data values. In some examples, a data value is enclosed within an opening tag and a closing tag of its corresponding attribute.
As an illustration, a computer system can store multiple objects that are each of a “purchase order” object type. A first of the objects can identify a purchase order from a first customer and a second of the objects can identify a purchase order from a second customer. Each of the purchase order objects may include a “Customer” attribute that was specified as required by a purchase order schema. The “Customer” data values may be different in each of the objects. For instance, the data value for the customer attribute in the first object may be “Customer B” while the data value for the customer attribute in the second object may be “Customer E.”
Data may be stored in markup language documents (e.g., XML (Extensible Markup Language) documents). Similar to the above-described objects, the XML documents may be generated based on a schema, and may include data elements that identify semantics of data values. The XML documents may be structured according to an XML schema (e.g., an XSD (“XML Schema Definition”) or a DTD (“Document Type Definition”)). An XML schema and a schema for an object type, however, may not be the same. For example, the attributes of the object schema may not be named the same as XML elements or attributes of an XML schema. As such, a system that is configured to interpret XML documents that were generated based on a particular XML schema may not be able to interpret the objects that include similar information but that were generated based on a non-XML object schema.